The invention relates to motor-fan units comprising a helicoid fan driven by an electric motor, and applies to those which are used to cool the motors of automobile vehicles. More precisely, it concerns the cooling of the electric motor.
Often this cooling cannot be ensured by the air stream created by the fan thereby posing problems. As a matter of fact, it is known that a helicoid fan has an output distinctly lower near its hub than near its periphery, so that it produces a mask effect and so that the air stream circulating against or in the electric driving motor may be insufficient to cool it properly. It is particularly the case with motor-fan units used for producing or speeding up the air stream passing through the radiator for cooling the circulation water of an automobile vehicle motor, in which the electric motor driving the fan often works with a mediocre output, especially if it is a two speed motor, and consequently dissipates a significant quantity of energy as heat.
Two speed motor-fan units, in which the slow speed is obtained by connecting a resistor in series in the supply circuit of the electric motor, poses, moreover, the problem of cooling this resistor. In addition, the fan of an apparatus for cooling by water is placed either in front of the radiator in order to blow the air through the latter or behind in order to draw the air through it. In the first instance, the electric motor is often at the suction side of the fan; in the second instance, this motor is often at the output side. The cooling apparatus of the electric motor must therefore be installed with due regard paid to the direction of the flow, in relation to this motor, of the air stream created by the helicoid fan.